Light emitting diode package structure

ABSTRACT

A light-emitting diode (LED) package structure including a carrier substrate, at least one LED chip, an optical element and a thermal-conductive transparent liquid is provided. The LED chip is disposed on the carrier substrate and has an active layer. The optical element is disposed on the substrate and forms a sealed space with the carrier substrate, and the LED chip is disposed in the sealed space. The thermal-conductive transparent liquid fills up the sealed space.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part application of and claims thepriority benefit of U.S. patent application Ser. No. 12/575,470, nowallowed, which claims the priority benefit of Taiwan application serialno. 98105780, filed on Feb. 24, 2009. The entirety of each of theabove-mentioned patent applications is hereby incorporated by referenceherein and made a part of specification.

TECHNICAL FIELD

The disclosure relates to a light emitting diode (LED) packagestructure.

BACKGROUND

In recent years, since the luminous efficiency of LED has beenconstantly improved, the LED gradually replaces a fluorescent lamp andan incandescent bulb in many fields, such as the light source of ascanner which requires high speed response, the backlight or front-lightsource of a liquid crystal display device, lighting for the dashboard ofa vehicle, traffic lights and common illumination devices. The LEDconverts electrical energy into light. When the electric current isapplied to the LED, energy is released in the form of light through thecombination of the electrons and holes, so as to achieve theillumination purpose.

FIG. 1 schematically illustrates a cross-sectional view of aconventional LED package structure. Referring to FIG. 1, theconventional LED package structure 100 includes a LED chip 110, acarrier substrate 120, conductive lines 132 and 134 and a moldingcompound 140. The LED chip 110 is disposed on the carrier substrate 120.Each of the conductive lines 132 and 134 electrically connects the LEDchip 110 and the carrier substrate 120. The molding compound 140 isdisposed on the carrier substrate 120 and covers the conductive lines132 and 134. A voltage difference is applied to the LED chip 110 throughthe conductive lines 132 and 134, and thereby an active layer 112 of theLED chip 110 emits light and generates thermal. If the heat generated bythe active layer 112 of the LED chip 110 cannot be released effectively,the LED chip 110 is easily damaged for being overheated particularlywhen it is driven in a high current.

SUMMARY

The disclosure provides a LED package structure, having a thermalconductive structure therein to enhance the thermal conductionefficiency of the whole package.

According to one embodiment, a LED package structure includes a carriersubstrate, at least one LED chip, an optical element and athermal-conductive transparent liquid. The carrier substrate includes aplurality of embedded channels or a plurality of conductive viastherein. The LED chip is disposed on the carrier substrate and has anactive layer. The optical element is disposed on the substrate and formsa sealed space with the carrier substrate, and the LED chip is disposedin the sealed space. The thermal-conductive transparent liquid fills upthe sealed space.

According to another embodiment, a LED package structure includes acarrier substrate, at least one thermal-conductive structure, at leastone LED chip, an optical element and a thermal-conductive transparentliquid. The thermal-conductive structure is disposed on the substrate.The LED chip is disposed over the carrier substrate. The optical elementis disposed on the carrier substrate and forms a sealed space with thecarrier substrate, and the thermal-conductive structure and the LED chipare disposed in the sealed space. The thermal-conductive transparentliquid fills up the sealed space.

In view of above, the thermal-conductive transparent liquid fills up thesealed space. Accordingly, the carrier substrate and thethermal-conductive structure below the LED chips help to increase thethermal conduction efficiency of the bottom of the LED chip, and thethermal-conductive transparent liquid in contact with the LED chip helpsto increase the thermal conduction efficiency of the sidewall and top ofthe LED chip.

In order to make the aforementioned and other objects, features andadvantages of the disclosure comprehensible, a preferred embodimentaccompanied with figures is described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide further understanding,and are incorporated in and constitute a part of this specification. Thedrawings illustrate exemplary embodiments and, together with thedescription, serve to explain the principles of the disclosure.

FIG. 1 schematically illustrates a cross-sectional view of aconventional LED package structure.

FIG. 2 schematically illustrates a LED package structure according to anembodiment of the disclosure.

FIG. 3 schematically illustrates a modification of the LED packagestructure in FIG. 2.

FIGS. 3A-3F schematically illustrate the structures of the LED chipsaccording to embodiments of the disclosure.

FIG. 4A schematically illustrates a LED package structure according toan embodiment of the disclosure.

FIG. 4B schematically illustrates a possible modification of the LEDpackage structure in FIG. 4A.

FIG. 5 schematically illustrates a LED package structure according to anembodiment of the disclosure.

FIGS. 6A and 6B schematically illustrate two kinds of modifications ofthe

LED package structure in FIG. 5.

FIG. 7A schematically illustrates a cross-sectional view of a LEDpackage structure according to another embodiment of the disclosure.

FIG. 7B schematically illustrates one possible modification of the LEDpackage structure in FIG. 7A.

DESCRIPTION OF EMBODIMENTS

FIG. 2 is a schematic cross-sectional view illustrating a LED packagestructure according to one embodiment. Referring to FIG. 2, a LEDpackage structure 200 includes a carrier substrate 210, a LED chip 220,an optical element 230 and a thermal-conductive transparent liquid 240.The carrier substrate 210 may be a thermal-conductive substrate, such asan aluminum oxide (Al₂O₃) substrate, an aluminum nitride (AlN)substrate, a copper substrate, a ceramic substrate or an aluminumsubstrate, etc. In this embodiment, the thermal conductivity of thethermal-conductive substrate is generally above 25 W/mK, for example.The LED chip 220 is disposed on the carrier substrate 210 and has anactive layer 228. The LED chip is electrically connected to the carriersubstrate 210 through wires C. In this embodiment, if a specific colorlight such as white light is required, a light conversion layer L isoptionally formed on the light emitting path of the LED chip 220. Indetails, the light conversion layer L can be directly attached to thesurface of the LED chip 220, so as to increase the uniformity of thelight. Alternatively, the light conversion layer L can be indirectlyattached to the surface of the LED chip 220. Further, to improve thethermal dissipation efficiency of the carrier substrate 210, a thermalsink (not shown) is optionally disposed on a surface 212 of the carriersubstrate 210 away from the LED chip 220.

The optical element 230 is disposed on the carrier substrate 210. Theoptical element 230 and the carrier substrate 210 form a sealed space S,and the LED chip 220 is disposed in the sealed space S. Specially, inthis embodiment, the optical element 230 is in arc shape and has arecess 232. The arc shape helps to increase the directivity of light.The carrier substrate 210 is disposed on an open side 232 a of therecess 232, so as to seal the recess 232 and form the sealed space S.The optical element 230 includes a material with high transparency suchas glass, for example. The optical element 230 is a lens, for example.In this embodiment, the optical element 230 is transparent with respectto at least a portion of the wavelength of the light emitted from theLED chip 220. For example, the optical element 230 is transparent withrespect to the wavelength of the visible light.

The material of the optical element 230 includes glass, epoxy resin ortransparent plastic, for example. The transparent plastic is olefinictransparent plastic or aliphatic transparent plastic (e.g. polypropyleneor polyethylene), and is not prone to degrade when in contact with theaprotic solvent such as a solution containing propylene carbonate. Thematerial of the transparent plastics is selected from the groupconsisting of cyclic olefin copolymers, polymethylpemtenes, hydrogenatedcyclo-olefin polymers and amorphous cyclo-olefin copolymers.

The thermal-conductive transparent liquid 240 fills up the sealed spaceS and is a liquid of high fluidity and high thermal conductivity. Inthis embodiment, the thermal conductivity of the thermal-conductivetransparent liquid 240 is greater than that of epoxy resin, and thelight transmittance of the thermal-conductive transparent liquid 240 ismore than about 50% with respect to the main wavelength of the lightemitted from the LED chip 220. The thermal-conductive transparent liquid240 directly contacts with the surface of the carrier substrate 210, theoptical element 230 and the LED chip 220 which are exposed to the sealedspace S. Therefore, through the flow of the thermal-conductivetransparent liquid 240, the heat generated by the LED chip 220 duringillumination is transferred to the carrier substrate 210 and the opticalelement 230, and then transferred to the outside of the LED packagestructure 200 through the carrier substrate 210 and the optical element230. In this embodiment, it is noted that the carrier substrate 210below the LED chip 220 helps to increase the thermal conductionefficiency of the bottom 222 of the LED chip 220, and thethermal-conductive transparent liquid 240 in contact with the LED chip220 helps to increase the thermal conduction efficiency of the sidewall224 and the top 226 of the LED chip 220.

In this embodiment, to avoid short circuit between electrodes E1 and E2of the LED chip 220, the thermal-conductive transparent liquid 240 is anelectric insulated liquid, for example. The material of thethermal-conductive transparent liquid 240 is selected from the groupconsisting of silicon oils, paraffin oils, olive oils, propylenecarbonate, perfluoropolyether (PFPE) and other liquids with highfluidity and high thermal conductivity. It is noted that when thethermal-conductive transparent liquid 240 is electricity-conductive, toavoid short circuit caused by the thermal-conductive transparent liquid240, an insulating layer (the material thereof includes an insulatingmaterial) I can be formed on the conductive parts (e.g. pads P) of theLED chip 220, the electrical connection parts (e.g. conductive lines C)of the LED chip 220 and a portion of the active layer on the sidewall ofthe LED chip 220. Alternatively, the light conversion layer covering theLED chip 220 can also function as an insulation between the conductiveparts and the thermal-conductive transparent liquid 240 when thethermal-conductive transparent liquid 240 is electricity-conductive.

In this embodiment, the thermal-conductive transparent liquid 240 maycontain a plurality of suspended particles 242. For example, thethermal-conductive transparent liquid 240 is deionized (DI) watercontaining titanium oxide (TiO₂) particles. The suspended particles 242can increase the refraction or reflection of the light emitted from theLED chip 220, so as to effectively increase the light emitting angle andavoid discomfort to the human eyes caused by the straight light.

The thermal-conductive transparent liquid 240 is a fluidic liquid underthe room temperature, and the viscosity thereof is less than about10,000 mPas, for example. In this embodiment, to prevent thethermal-conductive transparent liquid 240 from being frozen under lowtemperature, an antifreeze material such as methanol or ethylene glycolis added to the thermal-conductive transparent liquid 240, so as tomaintain the fluidity.

Further, the LED package structure 200 can optionally has a sealingmember 250. The sealing member 250 connects the carrier substrate 210and the outer periphery 234 of the optical element 230 and is disposedoutside the sealed space S. The material of the sealing member 250includes metal or alloy, for example. One suitable example of the alloyis Fe—Co—Ni alloy (known as Kovar alloy). The sealing member 250 isconnected to the carrier substrate 210 by metal to metal connection, soas to enhance the reliability of the connection between the sealingmember 250 and the carrier substrate 210.

In this embodiment, three methods for connecting the optical element 230to the sealing member 250 are provided for illustration purposes, andare not construed as limiting the disclosure. Method 1 is heating theoptical element 230 to the glass transition temperature or softeningtemperature and then mounting the sealing member 250 on the outerperiphery 234 of the optical element 230. Method 2 is metallizing (e.g.depositing metal such as titanium) the outer periphery 234 of theoptical element 230, and bonding the optical element 230 to the sealingmember 250 with solder (not shown). Method 3 is using a sealant (notshown) to bond the optical element 230 to the sealing member 250. Thecharacteristics of the sealant is similar to that of glass and thesoftening temperature of the same is lower (e.g. lower than 700° C.).

In this embodiment, two methods for connecting the carrier substrate 210to the sealing member 250 are provided for illustration purposes, andare not construed as limiting the disclosure. Method 1 is using aconnection layer 260 to bond the sealing member 250 to the carriersubstrate 210. The connection layer 260 is disposed between the sealingmember 250 and the carrier substrate 210, and the material thereofincludes metal or alloy (e.g. solder). The connection layer 260 isdesigned corresponding to the cross-sectional shape of the sealingmember 250, such as circular, quadrilateral, elliptic etc. Theconnection layer 260 can enhance the adhesion between the sealing member250 and the carrier substrate 210, so as to enhance the reliability ofthe whole package. Specifically, solder can be first formed on thecarrier substrate 210. Thereafter, the sealing member 250 which has beenconnected to the optical element 230 is disposed on the solder and thesolder is then heated.

FIG. 3 schematically illustrates a modification of the LED packagestructure in FIG. 2. Referring to FIG. 3, method 2 is fixing a fixedcomponent 270 on the carrier substrate 210. The method of fixing thefixed component 270 on the carrier substrate 210 is by bonding the fixedcomponent 270 to the carrier substrate 210 through solder (not shown) oradhesive (not shown) or co-sintering ceramics powder, or by forming thefixed component 270 and the carrier substrate 210 as a whole piece.Thereafter, the sealing member 250 which has been connected to theoptical element 230 is disposed on the fixed component 270. Afterwards,the connection portion between the sealing member 250 and the fixedcomponent 270 is heated by point discharge or laser welding, forexample. The fixed component 270 and the sealing member 250 include thesame material, such as Fe—Co—Ni alloy or Invar, for example.

Preferably, the growth substrate (i.e. the sapphire substrate or the SiCsubstrate) of the LED chip 220 is removed before or after joining theLED chip 220 to the carrier substrate 210 of the package structure 200for better thermal dissipation. As the LED chip 220 (without the growthsubstrate) is pretty thin, a conformal insulation layer 225 is formed tocover the top and the sidewalls of the LED chip 220 for betterprotection.

FIGS. 3A-3F schematically illustrate the structures of the LED chipsapplicable to the LED package structures according to severalembodiments of the disclosure. As shown in FIG. 3A-3C, the lightemitting chip 20 sequentially from bottom to top includes a firstelectrode layer 21, a first semiconductor layer 22, an active layer 23,a second semiconductor layer 24 and a second electrode 25. In principle,for better thermal dissipation, the growth substrate (i.e. the sapphiresubstrate or the SiC substrate) of the LED chip 20 is removed afterattaching the LED chip 20 to the package structure. Hence, the LED chip20 having no growth substrate is fixed to the substrate through abonding layer 26. The material of the bonding layer 26 may be aconductive adhesive material or a solder material, for example.

Referring to an embodiment shown in FIG. 3A, the second electrode 25 islocated on the top surface of the second semiconductor layer 24 and theLED chip 20 is electrically connected to the package structure throughthe conductive wire or line C.

Referring to an embodiment shown in FIG. 3B, the second electrode 25extends from the top surface of the second semiconductor layer 24, alongthe sidewall of the LED chip 20 and extends to the carrier substrate210, so as to electrically connect the LED chip 20 to the packagestructure. An insulating layer 28 is located between the secondelectrode 25 and the sidewall of the LED chip 20 for electricalinsulation.

Referring to an embodiment shown in FIG. 3C, the second electrode 25 islocated on the top surface of the carrier substrate 210, while atransparent conductive layer 27 extends from the top surface of thesecond semiconductor layer 24, along the sidewall of the LED chip 20 andconnects to the second electrode 25, so as to electrically connect theLED chip 20 to the package structure. An insulating layer 28 is locatedbetween the transparent conductive layer 27 and the sidewall of the LEDchip 20 for electrical insulation.

Referring to an embodiment shown in FIG. 3D, the LED chip 20 is a flipchip type LED, and the second electrodes 25 embedded in the channels Cand on the second semiconductor layer 24 are electrically connected tothe package structure through the bonding layer 26 filling in thechannels C. The second electrode 25 and the bonding layer 26 in thechannels C are isolated by the insulating layer 28.

As shown in FIG. 3E-3F, the light emitting chip 20 is a horizontal typelight emitting diode (LED), sequentially from bottom to top, including afirst semiconductor layer 22, an active layer 23 and a secondsemiconductor layer 24 located on the carrier substrate 210. The LEDchip 20 having no growth substrate is fixed to the carrier substrate 210through a bonding layer 26. In FIG. 3E, the first electrode layer 21 islocated on the first semiconductor layer 22, while the second electrode25 is located on the second semiconductor layer 24. The first and secondelectrodes 21, 25 are electrically connected to the package structurethrough the conductive wire or line C. Alternatively, referring to anembodiment shown in FIG. 3F, the second electrode 25 extends from thetop surface of the second semiconductor layer 24, along the sidewall ofthe LED chip 20 and extends to the top surface of the carrier substrate210, so as to electrically connect the LED chip 20 to the packagestructure. An insulating layer 28 is located between the top electrode25 and the sidewall of the LED chip 20 for electrical insulation. Thefirst electrode 21 extends from the top surface of the firstsemiconductor layer 22, along the sidewall of the LED chip 20 andextends to the carrier substrate 210 to electrically connect the LEDchip 20 to the package structure. When the bonding layer 26 is made of aconductive material, the first electrode 21 can be omitted, and the LEDchip 20 can be electrically connected to the external power sourcethrough the bonding layer 26 and the substrate 210.

All of the above described LED chips are applicable for the LED packagestructures of this disclosure. Although the LED chips shown in FIGS. 2-3may be horizontal type LEDs, other types of LED chips are alsoapplicable for the LED package structures of FIGS. 2-3 and suchmodification can be feasible for the LED package structures describedthereafter.

FIG. 4A schematically illustrates a cross-sectional view of a LEDpackage structure according to another embodiment. FIG. 4B schematicallyillustrates a modification of the LED package structure in FIG. 4A.Referring to FIG. 4A, a LED package structure 400 includes a carriersubstrate 210, a protrusion 410, a LED chip 220, an optical element 230and a thermal-conductive transparent liquid 240. Further, the LEDpackage structure 400 can optionally has a sealing member 250.

It is noted that the LED package structure 400 is similar to the LEDpackage structure 200 in FIG. 2, and the difference lies in that the LEDpackage structure 400 further has the protrusion 410. The differencebetween them is described in the following and the similar parts are notiterated herein.

The protrusion 410 is disposed on the carrier substrate 210 and has anopening OP to expose the carrier substrate 210. The material of theprotrusion 410 includes a thermal-conductive material, such as metal ormetal alloy. For example, the material of the protrusion 410 includesgold, silver, copper, indium, titanium, zinc, aluminum, lead, tin,nickel, platinum, chromium or a composite material with high thermalconductivity such as ceramics, for example.

The LED chip 220 is disposed on the carrier substrate 210 and in theopening OP. The protrusion 410 and the LED chip 220 are disposed in asealed space S formed by the optical element 230 and the carriersubstrate 210, and the thermal-conductive transparent liquid 240directly contacts the whole surface of the carrier substrate 210, theoptical element 230, the LED chip 220 and the protrusion 410 which areexposed to the sealed space S.

In other embodiments, if a specific color light is required, the depth Dof the opening OP is increased (i.e. the thickness of the protrusion 410is increased), so that the depth D of the opening OP is greater than theheight of the LED chip 220 (i.e. the top surface of the LED chip 220 islower than that of the protrusion 410), and fluorescent powder is filledin the opening OP.

The ratio of the cross-sectional width W1 of the opening OP to thecross-sectional width W2 of the LED chip 220 is larger than 1 andsmaller than or equal to 1.5. In this embodiment, it is noted that thecross-sectional width W1 of the opening OP and the cross-sectional widthW2 of the LED chip 220 are referred to the (smallest) width W1 of theopening OP and the (largest) width of the LED chip 220 in the samecross-section.

In view of above, the protrusion 410 is closer to the sidewall 224 ofthe LED chip 220, so that the protrusion 410 helps to increase thethermal conduction efficiency of the sidewall 224 of the LED chip 220.

In FIG. 4A, the ratio of the cross-sectional width W1 of the opening OPto the cross-sectional width W2 of the LED chip 220 is larger than 1 andsmaller than or equal to 1.5, so that a gap G exists between theprotrusion 410 and the sidewall 224 of the LED chip 220. An adhesivelayer F fills up the gap G, and the material thereof is selected fromthe group consisting of silver paste, solder, glass, alloy and othersuitable thermal-conductive materials, for example. Further, when theratio of the cross-sectional width W1 of the opening OP to thecross-sectional width W2 of the LED chip 220 is larger than 1 andsmaller than or equal to 1.5, the protrusion 410 and the carriersubstrate 210 can be formed as a whole piece or separate pieces. Inother words, the protrusion 410 and the carrier substrate 210 can beformed simultaneously, or formed separately and then assembled together.When the protrusion 410 and the carrier substrate 210 are formedseparately, each of the protrusion 410 and the carrier substrate 210includes a thermal-conductive material. In an embodiment, the materialof the protrusion 410 is the same as that the carrier substrate 210. Inanother embodiment, the material of the protrusion 410 is different fromthat of the carrier substrate 210 and is a heat-conductive material. Inyet another embodiment, the material of the protrusion 410 is partiallythe same as that of the carrier substrate 210.

Referring to FIG. 4B, in present embodiment, an adhesive layer 280 canbe disposed in the gap G and between the LED chip 220 and the carriersubstrate 210, so as to bond the LED chip 220 to the carrier substrate210 and the protrusion 410. The material of the adhesive layer 280 isselected from the group consisting of silver paste, solder, glass, alloyand other suitable thermal-conductive materials, for example. Therefore,the adhesive layer 280 helps to increase the thermal conductionefficiency of the LED chip 220.

As described above, in present embodiment, the heat generated by the LEDchip 220 during illumination is transferred to the carrier substrate 210or/and the protrusion 410 which is in contact with thethermal-conductive transparent liquid 240, and then transferred to theoutside of the LED package structure 400 through the carrier substrate210 and the thermal-conductive transparent liquid 240, so as to increasethe thermal conduction efficiency of the LED chip 220.

Further, in this embodiment, an intermediate layer 290 is formed on theinner wall A of the opening OP and on the portion of the carriersubstrate 210 exposed by the opening OP. Said layer 290 may reflect thelight emitted from the LED chip 220 and thus increase the light utility.The material of the intermediate layer 290, for example, includes silveror a material suitable for light reflection. Alternatively, the materialof the intermediate layer 290 may be made of light-absorbing ones. Inthis case, the intermediate layer 290 serves to absorb the light emittedfrom the edge side of the LED chip 220 so as to increase the uniformityof light output. In other embodiments (not shown), when the ratio of thecross-sectional width W1 of the opening OP to the cross-sectional widthW2 of the LED chip 220 is extremely close to 1, the sidewall 224 of theLED chip 220 is substantively attached to the protrusion 410.

FIG. 5 schematically illustrates a cross-sectional view of a LED packagestructure according to another embodiment. FIG. 6A and 6B schematicallyillustrates two kinds of modifications of the LED package structure inFIG. 5.

Referring to FIG. 5, the LED package structure 500 of this embodimentincludes a carrier substrate 210, a pedestal 510, a LED chip 220, anoptical element 230 and a thermal-conductive transparent liquid 240.Further, the LED package structure 500 can optionally have a sealingmember 250 and a fixed component (not shown).

It is noted that the LED package structure 500 is similar to the LEDpackage structure 200 in FIG. 2, and the difference lies in that the LEDpackage structure 500 further has the pedestal 510. The differencebetween them is described in the following and the similar parts are notiterated herein.

The pedestal 510 is disposed on the carrier substrate 210. The pedestal510 has a plurality of grooves T open to the carrier substrate 210 and afirst top surface 512 away from the carrier substrate 210. The materialof the pedestal 510 includes a thermal-conductive material, for example.The LED chip 220 is disposed on the first top surface 512 of thepedestal 510. The pedestal 510 and the LED chip 220 are disposed in thesealed space S. The thermal-conductive transparent liquid 240 directlycontacts the whole surface of the carrier substrate 210, the opticalelement 230, the LED chip 220 and the pedestal 510 which are exposed tothe sealed space. The thermal-conducive transparent liquid 240 fills upthe grooves T.

The grooves T of the pedestal 510 helps to increase the contact areabetween the pedestal 510 and the thermal-conductive transparent liquid240.

Accordingly, when the heat generated by the LED chip 220 is transferredto the pedestal 510, the heat is removed from the pedestal 510 throughthe flow of the thermal-conductive transparent liquid 240, and thus thethermal conduction efficiency of the pedestal 510 is increased.

The sealing member 250 has a second top surface 252 away from thecarrier substrate 210. The distance H1 between the first top surface 512of the pedestal 510 and the carrier substrate 210 is greater than orequal to the distance H2 between the second top surface 252 of thesealing member 250 and the carrier substrate 210. Consequently, the LEDchip 220 is elevated by the pedestal 510, so as to prevent the lightemitted from the LED chip 220 from being blocked by the sealing member250, thereby increasing the light extraction efficiency of the LEDpackage structure 500.

Referring to FIG. 6A, in this embodiment, the pedestal 510 includes abase 514 and a protrusion 516. The protrusion 516 is disposed on thebase 514 and has an opening OP to expose the base 514. The LED chip 220is disposed on the base 514 and in the opening OP. The ratio of thecross-sectional width W3 of the opening OP to the cross-sectional widthW4 of the LED chip 220 is larger than 1 and smaller than or equal to1.5. It is noted that the protrusion 516 is closer to the sidewall 224of the LED chip 220, so that the protrusion 516 helps to increase thethermal conduction efficiency of the sidewall 224 of the LED chip 220.

In FIG. 6A, the ratio of the cross-sectional width W3 of the opening OPto the cross-sectional width W4 of the LED chip 220 is larger than 1 andsmaller than or equal to 1.5, so that a gap G exists between the LEDchip 220 and the protrusion 516. An adhesive layer F fills up the gap G,and the material thereof is selected from the group consisting of silverpaste, solder, glass, alloy and other suitable thermal-conductivematerials, for example. The protrusion 516 is in contact with thethermal-conductive transparent liquid 240, so as to increase the thermalconduction efficiency of the sidewall 224 of the LED chip 220. The base514 and the protrusion 516 are formed as a whole piece, for example.

Referring to FIG. 6B, in this embodiment, an adhesive layer 280 can bedisposed in the gap G and between the LED chip 220 and the base 514, soas to bond the LED chip 220 to the base 514 and the protrusion 516. Thematerial of the adhesive layer 280 is selected from the group consistingof silver paste, solder, glass, alloy and other suitablethermal-conductive materials, for example. Therefore, the adhesive layer280 helps to increase the thermal conduction efficiency of the LED chip220. The base 514 of the pedestal 510 has a plurality of grooves Tembedded therein to assist heat dissipation.

Further, in this embodiment, an intermediate layer 290 is formed on theinner wall A of the opening OP and on the portion of the base 514exposed by the opening OP. The intermediate layer 290 may reflect thelight emitted from the LED chip 220 and thus increase the light utility.The material of the intermediate layer 290 may, for example, includesilver or a material suitable for light reflection. Alternatively, thematerial of the intermediate layer 290 may be made of light-absorbingones. In this case, the intermediate layer 290 serves to absorb thelight emitted from the edge side of the LED chip 220 so as to increasethe uniformity of light output.

In other embodiments, when the ratio of the cross-sectional width W3 ofthe opening OP to the cross-sectional width W4 of the LED chip 220 isextremely close to 1, the sidewall 224 of the LED chip 220 issubstantially attached to the protrusion 516. Therefore, the protrusion516 can transfer the heat generated by the LED chip 220 to the base 514and to the thermal-conductive transparent liquid 240, and then to thecarrier substrate 210, and the heat is then transferred to the outsideof the LED package structure through the carrier substrate 210 and thethermal-conductive transparent liquid 240. In light of theaforementioned description, the heat generated by the LED chip 220 canbe transferred to the protrusion 516 from the sidewall 224 of the LEDchip 220 so the protrusion 516 attached to the sidewall 224 availsincreasing the thermal conduction efficiency of the LED package.

FIG. 7A schematically illustrates a cross-sectional view of a LEDpackage structure according to another embodiment. FIG. 7B schematicallyillustrates one possible modification of the LED package structure inFIG. 7A.

Referring to FIG. 7A, in the embodiment, the LED package structure 700of this embodiment includes a carrier substrate 710, a LED chip 220, anoptical element 230 and a thermal-conductive transparent liquid 240.Further, the LED package structure 700 can optionally have a sealingmember 250 and a fixed component 270. The carrier substrate 710 furtherincludes a plurality of through-vias 720. The LED chip 220 canelectrically connected to the package structure 700 through thethrough-vias 720. The through-vias 720 can also help dissipate the heatfrom the LED chip 220.

Referring to FIG. 7B, in the embodiment, the carrier substrate 710 has aplurality of channels 730 embedded therein to assist heat dissipation.In some embodiments, the channels 730 can be connected to each other,and are not construed as limiting the disclosure. The channels 730 canalso comprise fluid therein to improve the thermal dissipationefficiency of the carrier substrate 710.

In summary, the carrier substrate below the LED chip helps to increasethe thermal conduction efficiency of the bottom of the LED chip, and thethermal-conductive transparent liquid in contact with the LED chip helpto increase the thermal conduction efficiency of the sidewall and top ofthe LED chip. By directly attaching the thinner LED chip without thegrowth substrate to the carrier substrate, the thickness of the packagestructure is reduced, which is beneficial for heat dissipation. Thesealing member is adopted to bond the optical element to the carriersubstrate, so as to fix the optical element on the carrier substrate toget a more reliable LED package. Further, the thermal conductionefficiency of the package structure can be increased by using theprotrusion closer to the sidewall of the LED chip, by elevating the LEDchip with the pedestal, or by providing conductive through-vias or thechannels in the carrier substrate beneath the LED chip. Moreover, as theLED chip is elevated by the pedestal, the light emitted from the LEDchip will not be blocked by the sealing member, thereby increasing thelight extraction efficiency of the LED package structure. In addition,even though the structure or electrical connection between the LEDpackage structure and LED chip and the structure or electricalconnection between the LED package structure and an external powerdevice are not described in the embodiments of the disclosure, thestructure or electrical connection between the LED package structure andLED chip and the structure or electrical connection between the LEDpackage structure and the external power device are well known to theone skilled in the art.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of thedisclosed embodiments without departing from the scope or spirit of thedisclosure. In view of the foregoing, it is intended that the disclosurecover modifications and variations of this disclosure provided they fallwithin the scope of the following claims and their equivalents.

1. A light emitting diode (LED) package structure, comprising: a carriersubstrate having a plurality of channels or a plurality of vias; atleast one LED chip, disposed on the carrier substrate and having anactive layer; an optical element, disposed on the carrier substrate andforming a sealed space with the carrier substrate, wherein the at leastone LED chip is disposed in the sealed space; and a thermal-conductivetransparent liquid, filling up the sealed space.
 2. The LED packagestructure of claim 1, further comprising a sealing member disposedoutside the sealed space, wherein the sealing member connects thecarrier substrate and an outer periphery of the optical element.
 3. TheLED package structure of claim 2, further comprising a fixed componentdisposed on the carrier substrate, wherein the fixed component connectsthe sealing member and the carrier substrate.
 4. The LED packagestructure of claim 2, further comprising a connection layer disposedbetween the sealing member and the carrier substrate, and a material ofthe connection layer comprises a metal or an alloy.
 5. The LED packagestructure of claim 1, wherein the thermal-conductive transparent liquidcomprises at least one antifreeze material.
 6. The LED package structureof claim 1, wherein the thermal-conductive transparent liquid contains aplurality of suspended particles.
 7. The LED package structure of claim1, wherein the thermal-conductive transparent liquid is an electricinsulated liquid.
 8. The LED package structure of claim 1, furthercomprising a light conversion layer disposed over the at least one LEDchip.
 9. The LED package structure of claim 8, wherein the lightconversion layer is directly adhered to a top surface and sidewalls ofthe at least one LED chip.
 10. The LED package structure of claim 1,further comprising an insulating layer on conductive parts of the atleast one LED chip and a portion of the active layer on sidewalls of theat least one LED chip.
 11. The LED package structure of claim 1, furthercomprising a conformal insulation layer covering a top surface andsidewalls of the at least one LED chip.
 12. A LED package structure,comprising: a carrier substrate; at least one thermal-conductivestructure disposed on the carrier substrate; at least one LED chip,disposed over the carrier substrate; an optical element, disposed on thecarrier substrate and forming a sealed space with the carrier substrate,wherein the at least one thermal-conductive structure and the at leastone LED chip are disposed in the sealed space; and a thermal-conductivetransparent liquid, filling up the sealed space.
 13. The LED packagestructure of claim 12, wherein the at least one thermal-conductivestructure includes a protrusion having an opening exposing the carriersubstrate and the at least one LED chip is located on the carriersubstrate and received within the opening, and a ratio of across-sectional width of the opening to a cross-sectional width of theat least one LED chip is larger than 1 and smaller than or equal to 1.5.14. The LED package structure of claim 12, wherein the at least onethermal-conductive structure includes a pedestal having at least onegroove and a first top surface away from the carrier substrate, and theat least one LED chip is located on the first top surface of thepedestal.
 15. The LED package structure of claim 14, wherein the atleast one groove of the pedestal is open to the carrier substrate andthe thermal-conductive transparent liquid fills up the at least onegroove.
 16. The LED package structure of claim 14, wherein the at leastone groove is embedded in the pedestal and the thermal-conductivetransparent liquid fills up the at least one groove.
 17. The LED packagestructure of claim 14, wherein the pedestal consists of a base and aprotrusion disposed on the base, the protrusion has an opening exposingthe base, and the at least one LED chip is disposed on the base exposedby the opening.
 18. The LED package structure of claim 17, wherein aratio of a cross-sectional width of the opening to a cross-sectionalwidth of the at least one LED chip is larger than 1 and smaller than orequal to 1.5.
 19. The LED package structure of claim 14, furthercomprising a sealing member disposed outside the sealed space andconnecting the carrier substrate and an outer periphery of the opticalelement, wherein the sealing member has a second top surface away fromthe carrier substrate, and a distance between the first top surface ofthe pedestal and the carrier substrate is greater than or at least equalto a distance between the second top surface of the sealing member andthe carrier substrate.
 20. The LED package structure of claim 19,further comprising a fixed component disposed on the carrier substrate,wherein the fixed component connects the sealing member and the carriersubstrate.